L'Engle and the Dehumanizing Effects of Victimhood

From Madeleine L'Engle's book Walking on Water:

Sin, that unpopular word again. The worse things get, the more we try to rationalize and alibi. When we do wrong we try to fool ourselves (and others) that it is because our actions and reactions have been coded into our genetic pattern at the moment of conception. Or our mothers didn't understand us. Or they understood us too well. Or it is the fault of society. Certainly it is never our fault, and therefore we have not sinned.
[By] such dirty devices, any shred of free will left in the human being is taken away. If I do wrong, I may do it unwittingly, thinking I am doing something for the best; but if it turns out to be wrong, I have done it, and I must bear the responsibility. It is not somebody else's or something else's fault. If it is, [then] I am less than human.